It is known in the art to seal or fill electrical and electronic components with organopolysiloxane compositions curable by a hydrosilylation reaction. Such compositions can be exemplified, e.g., by the following: a composition that comprises a branched-chain organopolysiloxane having vinyl groups, a linear-chain organopolysiloxane having silicon-bonded hydrogen atoms, and a hydrosilylation reaction catalyst {see Japanese Unexamined Patent Application Publication (hereinafter referred to as “Kokai”) S48-17847}; a composition that comprises a branched-chain organopolysiloxane having vinyl groups, an organopolysiloxane having silicon-bonded hydrogen atoms, and a hydrosilylation reaction catalyst (see Kokai S58-7452); and a composition that comprises a branched-chain organopolysiloxane having vinyl groups, a linear-chain organopolysiloxane capped at both molecular terminals with vinyl groups, a linear-chain organopolysiloxane having silicon-bonded hydrogen atoms only at both molecular terminals, and a hydrosilylation reaction catalyst (see Japanese Examined Patent Application Publication H03-19269).
In general, the compositions of the aforementioned type are cured by heating. Recently, however, in order to protect the environment, investigations were carried out aimed at decreasing amounts of CO2 formed during sealing or filling of electric and electronic components associated with heating.
However, curing of the aforementioned compositions at room temperature results, either in incomplete curing, or produces cured bodies of insufficient hardness. Furthermore, reliability testing of electric and electronic components sealed or filled with the aforementioned composition reveals that hardness of a cured body changes with the lapse of time thus impairing reliability of the sealed or filled components.
It is an object of the present invention to provide a sealant or filler for electrical and electronic components that ensures sufficient curing at room temperature and makes it possible to improve reliability of the sealed or filled components. It is another object to provide electrical and electronic components that possess sufficient reliability.